Tommy Y. Choi
STAT200 OL1
Chapter 42 Questions:
14)
Identifying Probability Values
a) What is the probability of an event that is certain to occur?
b) What is the probability of an impossible event?
c) A sample space consists of 10 separate events that are equally
likely.
What is the probability of each?
d) On a true/false test, what is the probability of answering a
question correctly if you make a random guess?
e)
On a multiplechoice test with five possible answers for each
question, what is the probability of answering a question
correctly if you make a random guess?
a)
Certain To Occur
:
1
b)
Impossible Event
: 0
c)
1 / 10 = 0.1
10%
d)
1 / 2 = 0.5
50%
e)
1 / 5 = 0.2
20%
28) Using probability to Identify Unusual Events:
Consider an event
to be “unusual” if its probability is less than or equal to 0.05. (This is
equivalent to the same criterion commonly used in inferential
statistics, but the value of 0.05 is not absolutely rigid, and other values
such as 0.01 are sometimes used instead.)
a)
Bumped From A Flight:
Among 15,378 Delta airline passengers
randomly selected, 3 were bumped from a flight against their
wishes (Based on data from the U.S. Department of
Transportation).
Find the probability that a randomly selected
passenger is involuntarily bumped.
Is such bumping unusual?
Does such bumping pose a serious problem for Delta passengers
in general?
Why or why not?
a)
Probability
: 0.000195
a.
3 / 15,378
b. Being bumped off a flight on Delta is unusual since the
probability of 0.000195< 0.05.
As a Delta passenger, it
is not a serious problem being bumped off your flight
since the event is unusual and will probably not occur.
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STAT200 OL1
Chapter 43 Questions
4) Addition:
When analyzing results from a test of the Microsort gender
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 Fall '10
 Hirschorn
 Statistics, Probability, Randomness, Tommy Y. Choi

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